Survival
appeared to be the biggest challenge.
But rather than the open-ground, the most vulnerable proved to be the root trainer –raised plants.
This result, from the Sandspit Road trial, like so many aspects of the open-ground project, and the method itself, is entirely counter-intuitive. Logic would have suggested that the less a plant’s root system was disturbed during transplantation, the less transplantation shock, and associated mortality, would be involved.
The particular vulnerability of root trainer plants is the ease with which they can be dislodged, particularly the smaller of the two sizes in common use, Hillsons, which are used in the trial.
Te köuka (cabbage tree) is vastly over-represented in the plants recorded as missing or dead. Te köuka roots are known to be of particularly interest to pükeko, suggesting that the indigenous swamp hen is the main culprit. The trial situation whereby an entire row can consist of lightweight, root trainer te köuka, and the adjacent wetland, must present unprecedented convenience for pükeko—illustrated by the pattern of greatest losses being contiguous and at the end of the row closest to the water.
In four of the six species, planter bag or potted plants (PB3-size) suffered negligible losses.
However only in three species did the open-ground plants boast negligible losses.
The one open-ground species that outperformed the planter bag or potted plants was karamü, which is known to strike very readily. But it did not excel by much—98.8% survival rate, compared to the competition at 91.3% and 90% respectively.
Open-ground and root trainer mänuka suffered uniformly large losses compared to 100% survival of the PB3-sized containers. This would appear to reflect the famous sensitivity of mänuka to having its root system disturbed.
The largest losses from a single species were of koromiko—open-ground fared worst, at 72.5%—probably the result of browsing by rabbits.
Given that the open-ground plants received no additional treatment aimed at reducing transplantation shock, the trial results shows them as having comparable survival rates to planter bag or potted plants, and far superior to those of the Hillson-sized root trainers.
Although the survival rates of potted plants were somewhat better, they were also twice the price.
With a little more work, open-ground seems set to make up for lost ground.
Coming section Silver-Tongued Strategy
Previous section Less-Shocking Systems
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Part of a hope-based network restoring and enjoying the Mahurangi
Editor Cimino Cole
Deadline for submissions Midnight 31 May
Click to make a quick five-minute submission.
Not perfect but a Field day and a half
The Mahurangi Action Plan –inspired Open-Ground and
Head for the Bar: Open-ground plants hold their own with planter bag and potted, and surpass root trainer in the survival stakes—although none were literally staked!